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From: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
To: "YOSHIFUJI Hideaki / 吉藤英明" <yoshfuji@linux-ipv6.org>
Cc: herbert@gondor.apana.org.au, davem@redhat.com, netdev@oss.sgi.com
Subject: Re: [INET] Optimise away a branch in IP_ECN_set_ce
Date: Wed, 8 Sep 2004 21:27:57 -0300	[thread overview]
Message-ID: <200409082127.57827.acme@conectiva.com.br> (raw)
In-Reply-To: <20040909.092428.125540781.yoshfuji@linux-ipv6.org>

Em Qua 08 Set 2004 21:24, YOSHIFUJI Hideaki / 吉藤英明 escreveu:
> In article <20040909000330.GA5581@gondor.apana.org.au> (at Thu, 9 Sep 2004 
10:03:31 +1000), Herbert Xu <herbert@gondor.apana.org.au> says:
> > +       u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
> >
> > + /*
> > +  * The following gives us:
> > +  * INET_ECN_ECT_1 => check += __constant_htons(0xFFFD)
> > +  * INET_ECN_ECT_0 => check += __constant_htons(0xFFFE)
> > +  */
> > + if (__constant_htons(1) != 1)
> > +  ecn <<= 8;
> > + check += __constant_htons(0xFFFB) + ecn;
> > +
> >   iph->check = check + (check>=0xFFFF);
> >   iph->tos |= INET_ECN_CE;
> >  }
>
> s/__constant_htons/htons/g here, please.

For Herbert understanding: the generated code is the same in this case. :)

>
> And, I think
>   u16 ecn = (iph->tos + 1) & INET_ECN_MASK;
>
>   check += (u32)htons(0xfffb) + (u32)htons(ecn);
>
> or something like that?

  reply	other threads:[~2004-09-09  0:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-09  0:03 [INET] Optimise away a branch in IP_ECN_set_ce Herbert Xu
2004-09-09  0:24 ` YOSHIFUJI Hideaki / 吉藤英明
2004-09-09  0:27   ` Arnaldo Carvalho de Melo [this message]
2004-09-09  0:36     ` YOSHIFUJI Hideaki / 吉藤英明
2004-09-09  0:53       ` Arnaldo Carvalho de Melo
2004-09-09  1:10   ` Herbert Xu
2004-09-09  1:27     ` YOSHIFUJI Hideaki / 吉藤英明
2004-09-09  1:54       ` Herbert Xu
2004-09-09  1:58         ` YOSHIFUJI Hideaki / 吉藤英明
2004-09-09  4:35           ` David S. Miller

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